Stainless steel is an alloy of iron, chromium, and sometimes nickel that is known for its corrosion resistance and strength. It requires a minimum of 10.5-11% chromium content to give it good corrosion resistance through the formation of a passive chromium oxide layer. There are several types of stainless steel including austenitic, ferritic, martensitic, duplex, and precipitation hardening grades, each with different microstructures and properties. Stainless steel finds wide application in industries such as medical, chemical processing, marine, and automotive due to its corrosion resistance.

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INTRODUCTION
Stainless Steel is a type of steel
that is characterized primarily by
their corrosion resistance, high
strength and ductility , and High
Chromium Content.
HISTORY
The corrosion resistance of
Iron-Chromium alloys was first
recognized in 1821 by the French
Metallurgist “Pierre Breathier”.
In the year 1904-1911, several
researchers, particularly Leon
Gullet of France, prepared
alloys that would today be
considered “STAINLESS STEEL”CATEGORY
High Alloy Steels ,
Ferrous Metal .

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COMPOSITIO
NMinimum
Chromium % is
about 10.5 –
11% by Weight .
Carbon Ranges
from 0.2 – 2.14
% .

5. EFFECT OF ALLOYING ELEMENTS ON
STAINLESS STEEL .

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TYPES

7. Let’s Discuss About one of
those Type……..!
Excellent corrosion
resistance and good
resistance to intergranular
corrosion .
Excellent hot and cold
forming process and
performance .
Good low temperature
performance.
Superior Resistance to
Chloride
Resistance to Corrosive
Chemicals .
Better Resistance to

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STAINLESS
STEEL TREE
STRUCTURE

9. The four steel grades described above, belonging to
various levels of the tree structure of stainless steels ,
also represent the four main families of stainless steels
currently used ; these families , all defined on the basis
of their microstructure at ambient temperature, are:
1) Martensitic stainless steel (such as
X30Cr13),
2) Ferritic stainless steel
(such as X6Cr17),
3) Austenitic stainless steel (such
as X5CrNi18-10 and X5CrNiMo17-12-2),
4) Austen-ferritic, two-phase or duplex stainless steel
(such as X2CrNiMoN22-5-3).
A fifth category can be added to these four, i.e. the
family of stainless steels by
5) Precipitation Hardening : this is not defined by the
metallurgical structure of the steel at ambient
temperature but rather, as per tradition , by the heat
treatment/strengthening mechanism used to produce it (

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DESCRIPTION
• These steels are based
on Chromium with small
amounts of Carbon usually
less than 0.10%.
• They have a similar
microstructure to carbon
and low alloy steels.
• They are usually
limited in use. Ferritic
steels are also chosen
for their resistance to
FERRITIC

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AUSTENITIC
• These steels are the most
common. Their microstructure is
derived from the addition of
Nickel, Manganese and Nitrogen.
• This structure gives these
steels their characteristic
combination of weld ability and
formability.
• They cannot be hardened by
heat treatment but have the
useful property of being able
to be work hardened to high
strength levels whilst
retaining a useful level of
ductility and toughness.

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MARTENSITIC
• These steels are similar
to ferritic steels in
being based on Chromium
but have higher Carbon
levels up to as high as
1%.
• This allows them to be
hardened and tempered much
like carbon and lowalloy
steels.
• They are used where
high strength and moderate
corrosion resistance is
required.

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DUPLEX
• These steels have a
microstructure which is
approximately 50% ferritic
and 50% austenitic. This
gives them a higher
strength than either
ferritic or austenitic
steels.
• They are resistant to
stress corrosion cracking.
• They are weldable but
need care in selection of
welding consumables and
heat input.

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PRECIPITATION HARDENING
• These steels can develop very high
strength by adding elements such as
Copper, Niobium and Aluminium to the
steel.
• With a suitable “aging” heat treatment,
very fine particles form in the matrix of
the steel which imparts strength.
• These steels can be machined to quite
intricate shapes requiring good
tolerances.
• Corrosion resistance is comparable to
standard austenitic steels

16. PROPERTIES OF STAINLESS STEEL
HARDNESS
(Brinell
3000Kg)
137-595
SPECIFIC HEAT
(J/Kg-K)
420-500
YIELD STRENGTH
(Mpa)
207-552
ELASTIC
MODULUS (Gpa)
190-210
TENSILE
PROPERTIES
MELTING POINT
(^C)
1371-1454
TENSILE
STRENGTH (Mpa)
515-827
DENSITY
(1000Kg/M^3)
7.75-8.1
PERCENT
ELONGATION (%)
12-40
ELECTRICAL
RESISTIVITY
(10-9 OHM-M)
75.7-1020
POISSON’S
RATIO
0.27-0.3
MECHANICAL
PROPERTIES

17. CHEMICAL
PROPERTIES
Chromium is added to steel to make
to make it Resistant to Rust.
Stainless Steel forms a passivation
layer of Chromium (III) Oxide.
When the Chromium Layer is damaged
Chemically or Mechanically it Repairs
itself
Assuming Oxygen ( even in very small
amounts) is Present.
The Other minor constituents of steel are
Nickel, Nitrogen , Molybdenum and
Aluminium.
Nickel Increase the Corrosion resistance
further.
Stainless steel have
resistance to
oxidation(rust)and
corrosion in many
natural and man made
environments.

18. PHYSICAL
PROPERTIES
STREGTH
Stainless steel is very
strong. This form of
steel can withstand
very high and very
low heats while still
maintaining a solid
but flexible shape.
STAINRESISTANCE
The steel is
also
unlikely to
deteriorate
or rust as
other
metals are
known to
do. This lack
of
permeability
and
chemical
reaction
helps the
stainless
steel maintain
its initial
integrity and
CONDUCTIVITY
Stainless steel
is not
known as a good
conductor of
heat or
electricity,
which makes the
material
safe in the
construction,
manufacturing
and
cooking
industries.

19. The steelmaking process starts with the processing of iron ore.
The rock containing iron ore is ground and the ore is extracted
using magnetic rollers. Fine-grained iron ore is processed into
coarse-grained clumps for use in the blast furnace.
Coal is cleaned of impurities in a coke furnace, yielding an
almost pure form of carbon.
A mixture of iron ore and coal is then heated in a blast furnace

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MANUFACTURING
PROCESS
The manufacture of stainless
steel involves a series of
processes.
• The raw materials are
melted together in an
electric furnace. This step
usually is 8 to 12 hours of
intense heat.
• Next, the mixture is cast
into one of several shapes,
these include blooms
(rectangular shapes), billets
(round or square shapes) and

21. After steel
goes through
forming
operations,
beginning with
hot rolling, in
which the steel
is heated and
passed through
huge rolls.
Blooms and
billets are formed
into bar and wire,
while slabs are
formed into plate,
strip, and sheet.
Bars are available
in all grades and
come in rounds,
squares, octagons,
or hexagons.
After the
stainless steel is
formed, most types
must go through an
annealing step.
Annealing is a
heat treatment in
which the steel is
heated and cooled
under controlled
conditions to
relieve internal
stresses and

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• Annealing causes a scale or build-up to form on the steel. The scale
can be removed using several processes. One of the most common
methods:
Pickling,uses a nitric-hydrofluoric acid bath to descale the steel.
Electro cleaning, an electric current is applied to the surface using
acathode and phosphoric acid, and the scale is removed.
• The annealing and descaling steps occur at different stages
depending on the type of steel being worked.
• Bar and wire go through further forming steps (more hot rolling,
forging, or extruding) after the initial hot rolling before being
annealed and descaled.
• Sheet and strip, on the other hand, go through an initial annealing
and descaling step immediately after hot rolling.
• After cold rolling (passing through rolls at a relatively low
temperature), which produces a further reduction in thickness, sheet

23. • Surface finish is an important specification for stainless steel products. A
smooth surface as obtained by polishing also provides better corrosion
resistance. There are a variety of methods used for finishing:
A dull finish is produced by hot rolling, annealing, and descaling.
A bright finish is obtained by first hot rolling and then cold rolling on
polished rolls.
A highly reflective finish is produced by cold rolling in combination with
annealing in a controlled atmosphere furnace, by grinding with abrasives, or by
buffing a finely ground surface.
• After the stainless steel in its various forms are packed and shipped to the
fabricator or end user, a variety of other processes are needed.
• Further shaping is accomplished using a variety of methods, such as roll
forming, press forming, forging, press drawing, and extrusion.

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CHARACTERISTI
CSThe characteristics of the
broad group of stainless
steels can be viewed as
compared to the more familiar
plain carbon "mild" steels.
As a generalisation the
stainless steels have:
Higher work hardening rate
Higher ductility
Higher strength and hardness
Higher hot strength
Higher corrosion resistance
Higher cryogenic toughness
Lower magnetic response
(austenitic only)
Must retain corrosion
resistant surface in the

25. ALLOY GROUP MAGNETIC
RESPONSE
WORK HARDENING
RATE
CORROSION
RESISTANCE
HARD ENABLE
AUSTENITIC Generally NO Very high High By Cold Work
DUPLEX Yes Medium Very High No
FERRITIC Yes Medium Medium No
MARTENSITIC Yes Medium Medium Quench &
Temper
PRECIPITATION
HARDENING
Yes Medium Medium Age Harden

26. ALLOY GROUP DUCTILITY HIGH
TEMPERATURE
RESISTANCE
LOW
TEMPERATURE
RESISTANCE
WELDABILITY
AUSTENITIC Very High Very High Very High Very High
DUPLEX Medium Low Medium High
FERRITIC Medium High Low Low
MARTENISTIC Low Low Low Low
PRECIPITATION
HARDENING
Medium Low Low High

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APPLICATION
S OF
STAINLESS
STEEL
Stainless steel is an
attractive material for a
variety of applications,
usually due to the
corrosion resistance and
strength. Amongst the
fields which make great
use of stainless
steel are the following:

28. MEDICAL &
SURGERY
EQUIPMENT
MARINE ,
TURBINE
AUTOMATIV
E
INDUSTRY
CHEMICAL AND
PETROCHEMICAL
INDUSRY

29. bulk materials handling equipment
building exteriors and roofing
automobile components (exhaust, trim/decorative, engine, fasteners, tubing)
chemical processing plants (scrubbers and heat exchangers)
pulp and paper manufacturing
petroleum refining,
water supply piping
consumer products
marine and ship building
pollution control
sporting goods (snow skis)
transportation (rail car)

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